The purpose of this contract is to isolate and identify the peptides of collagen, and to identify the specific membranes that inhibit collagen interaction. In addition, the principal investigator will synthesize collagen-like peptides that will react with platelets and that can be made to inhibit collagen platelet interaction. The antigen bromide peptides that will be investigated include Alpha 1CB 6,8, Alpha 2CD 5, and Alpha 2CB2. The screening procedure to be used is an assay system based on Serotonin release from platelets.